about writing to the registry:
look in the location i gave youin the registry
hkcu\software\microsoft\office/12.0/access/security/trustedlocations
it has sub "folders" each of which is a trusted location (use a pc with full access with manually added trusted locations to identify the structure)
you can even copy an existing one, then change it's values to add a new one
if you need help in writing to the registry by api, ask. (and remember writing directly to the registry is something to consider thoughtfully.)